If you're talking about the metal buildings like this
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Like we have at work, basically one of those carports with sides and doors, all metal frame, this one leaks some when it rains, not as bad as leaving the stuff inside out in the elements obviously, but you have to watch where you put sensitive stuff. I'm sure some of that was installer error. I hate the cheap roll up doors too.
If you were going to insulate and drywall it'll need more work and money to finish for sure. I think this one cost my boss 6000 or so 10 years ago or better. I built my pole barn in 04 for $20000 ish. But mines not finished inside, it is barely insulated. the one pictured has no insulation or electric either